Discovering physical cell identifiers in wireless communications

ABSTRACT

Aspects of the present disclosure describe receiving, in a portion of bandwidth, a unified synchronization signal from one or more cells in a zone, and receiving, in the portion of bandwidth, a cell-specific signal from at least one cell of the one or more cells in the zone.

CLAIM OF PRIORITY UNDER 35 U.S.C. § 119

The present Application for Patent is a continuation of application Ser.No. 16/104,726 entitled “DISCOVERING PHYSICAL CELL IDENTIFIERS INWIRELESS COMMUNICATIONS” filed Aug. 17, 2018, which is a continuation ofapplication Ser. No. 15/371,782 entitled “DISCOVERING PHYSICAL CELLIDENTIFIERS IN WIRELESS COMMUNICATIONS” filed Dec. 7, 2016, which claimspriority to Provisional Application No. 62/329,909 entitled “DISCOVERINGCELL IDENTIFIERS IN WIRELESS COMMUNICATIONS” filed Apr. 29, 2016, whichare assigned to the assignee hereof and hereby expressly incorporated byreference herein for all purposes.

BACKGROUND

Aspects of the present disclosure relate generally to wirelesscommunication systems, and more particularly, to wireless communicationsystems for indicating and discovering physical cell identifiers.

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be multiple-accesssystems capable of supporting communication with multiple users bysharing the available system resources (e.g., time, frequency, andpower). Examples of such multiple-access systems include code-divisionmultiple access (CDMA) systems, time-division multiple access (TDMA)systems, frequency-division multiple access (FDMA) systems, andorthogonal frequency-division multiple access (OFDMA) systems, andsingle-carrier frequency division multiple access (SC-FDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. For example, a fifth generation (5G)wireless communications technology (which can be referred to as 5G newradio (5G NR)) is envisaged to expand and support diverse usagescenarios and applications with respect to current mobile networkgenerations. In an aspect, 5G communications technology can include:enhanced mobile broadband addressing human-centric use cases for accessto multimedia content, services and data; ultra-reliable-low latencycommunications (URLLC) with certain specifications for latency andreliability; and massive machine type communications, which can allow avery large number of connected devices and transmission of a relativelylow volume of non-delay-sensitive information. As the demand for mobilebroadband access continues to increase, however, further improvements in5G communications technology and beyond may be desired.

For example, for 5G communications technology and beyond, currentnetwork-centric media access control (MAC) layer technologies may notprovide a desired level of resource utilization and/or efficiencybecause of the various associated signal broadcasts. Further, thesebroadcasts consume power and may or may not be received or used by someor all of a cell's UEs. Additionally, a wireless communication systemhaving a network-centric MAC layer also places relatively more of thenetwork processing on user equipment (UE) (e.g., a UE identifies a firstserving cell upon initially accessing the network, and then identifiesand monitors handover targets (other serving cells) as part of itsmobility management).

Thus, improvements in wireless communication systems may be desired.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

According to an example, a method for wireless communications isprovided. The method includes receiving, in a portion of bandwidth, aunified synchronization signal from one or more cells in a zone, andreceiving, in the portion of bandwidth, a cell-specific signal from atleast one cell of the one or more cells in the zone.

In another example, an apparatus for wireless communications isprovided. The apparatus includes a transceiver, a memory configured tostore instructions, and a processor coupled to the transceiver and thememory. The processor is configured to execute the instructions toreceive, in a portion of bandwidth, a unified synchronization signalfrom one or more cells in a zone, and receive, in the portion ofbandwidth, a cell-specific signal from at least one cell of the one ormore cells in the zone.

In another example, an apparatus for wireless communications is providedthat includes means for receiving, in a portion of bandwidth, a unifiedsynchronization signal from one or more cells in a zone, and means forreceiving, in the portion of bandwidth, a cell-specific signal from atleast one cell of the one or more cells in the zone.

In another example, a computer-readable medium storing code executableby a processor for wireless communications is provided. The codeincludes code for receiving, in a portion of bandwidth, a unifiedsynchronization signal from one or more cells in a zone, and receiving,in the portion of bandwidth, a cell-specific signal from at least onecell of the one or more cells in the zone

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed aspects will hereinafter be described in conjunction withthe appended drawings, provided to illustrate and not to limit thedisclosed aspects, wherein like designations denote like elements, andin which:

FIG. 1 illustrates an example of a wireless communication system, inaccordance with various aspects of the present disclosure;

FIG. 2 illustrates an example of a zone of cells in a user equipment(UE)-centric media access control (MAC) (UECM) network in accordancewith various aspects of the present disclosure;

FIG. 3 is a block diagram illustrating an example of a base station, inaccordance with various aspects of the present disclosure;

FIG. 4 is a block diagram illustrating an example of a UE, in accordancewith various aspects of the present disclosure;

FIG. 5 is a flow chart illustrating an example of a method fortransmitting measurement reference signals, in accordance with variousaspects of the present disclosure;

FIG. 6 is a flow chart illustrating an example of a method fordiscovering physical cell identifiers, in accordance with variousaspects of the present disclosure;

FIG. 7 is a block diagram illustrating an example of bandwidth used totransmit various synchronization signals in wireless communications, inaccordance with various aspects of the present disclosure; and

FIG. 8 is a block diagram illustrating an example of a MIMOcommunication system including a base station and a UE, in accordancewith various aspects of the present disclosure.

DETAILED DESCRIPTION

Various aspects are now described with reference to the drawings. In thefollowing description, for purposes of explanation, numerous specificdetails are set forth in order to provide a thorough understanding ofone or more aspects. It may be evident, however, that such aspect(s) maybe practiced without these specific details.

The described features generally relate to a wireless communicationsystem having a user equipment (UE)-centric media access control (MAC)layer and/or for performing UE-centric or uplink-based mobility. Forexample, a wireless communication system having a UE-centric MAC layermay be advantageous, in some respects, in a time-domain duplex (TDD)system having a large antenna array, as the large antenna array may havelimited coverage for broadcast channels (e.g., the channels thatbroadcast synchronization signals and system information in a wirelesscommunication system having a network-centric MAC layer and/or forperforming network-centric or downlink-based mobility). As described inthe present disclosure, a wireless communication system having aUE-centric MAC layer and/or for providing UE-centric or uplink-basedmobility may forego the broadcast of system information, as well as somecell-specific signals, and instead transmit these signals when requestedby a UE.

In an example, cells of the network may broadcast synchronizationsignals to the UEs, where the synchronization signals may include anidentifier of a zone. For example, a “cell” can refer to a base station,a carrier or component carrier associated with a base station, or acoverage area (e.g., sector, etc.) of a carrier or base station,depending on context. A zone may include a plurality of cells operatingon the same frequency and/or with the same timing, etc., such that ahandover from one cell to another within the zone may be controlled bythe network and transparent to the UE. Accordingly, the UE may acquire atiming of cells within the zone (e.g., based on detecting zone-specificsynchronization signals transmitted by one or more of the cells).

It may be advantageous, however, for the UE to determine physical cellidentifiers specific to one or more cells within the zone (e.g., asopposed to only a physical identifier of the zone). For example, thecells may communicate control data encoded based on a physical cellidentifier. As another example, the UE may desire to performinterference cancellation. As yet another example, the UE may desire todetermine signal-to-noise ratio (SNR) of neighboring cells. As a furtherexample, the UE may desire to perform mobility management. In suchcases, the physical cell identifier of a serving cell for the UE and/orneighboring cells may assist in performing these (or other) functions.

As such, according to the present description, in one aspect, a cell maybe configured to indicate its physical cell identifier to a UE bytransmitting one or more cell-specific signals. In an example, the cellmay transmit measurement reference signals (MRS) as the cell-specificsignals to one or more UEs, where the MRS can include a physical cellidentifier. For example, the MRS may be scrambled using the physicalcell identifier, such that the UE may be configured to determinephysical cell identifiers associated with one or more MRSs based on ascrambling sequence of the MRS(s). For example, the MRS can refer to adownlink cell-specific reference signal transmitted by a cell, which canbe used for primary broadcast channel (PBCH) (or other channel)demodulation, downlink measurement for downlink based mobility, trackingloops (e.g., frequency tracking loops, time tracking loops, etc.).

In another example, the cell may transmit a cell-specificsynchronization signal as the cell-specific signal that otherwiseindicates the physical cell identifier (e.g., based on sequences havinggood cross-correlation properties such as m-sequences, Zadoff-Chusequences, etc.). For example, the UE may determine a serving physicalcell identifier based at least in part on attempting to decode a controlchannel from the serving cell based on one or more of the determinedphysical cell identifiers.

In addition, in yet another example, the network can determine astrongest cell for the UE (e.g., based on the cells measuring a strengthof a signal received from the UE), and may transmit the cell-specificsignal on the strongest cell. In this example, the UE may additionallyor alternatively determine the serving cell as the cell from which thecell-specific signal is received. In some examples, the network maytransmit the cell-specific signal from the strongest cell and/orcell-specific signals from other cells in the zone based on a requestfrom the UE or other conditions, as described further herein.

The described features will be presented in more detail below withreference to FIGS. 1-8.

As used in this application, the terms “component,” “module,” “system”and the like are intended to include a computer-related entity, such asbut not limited to hardware, firmware, a combination of hardware andsoftware, software, or software in execution. For example, a componentmay be, but is not limited to being, a process running on a processor, aprocessor, an object, an executable, a thread of execution, a program,and/or a computer. By way of illustration, both an application runningon a computing device and the computing device can be a component. Oneor more components can reside within a process and/or thread ofexecution and a component can be localized on one computer and/ordistributed between two or more computers. In addition, these componentscan execute from various computer readable media having various datastructures stored thereon. The components can communicate by way oflocal and/or remote processes such as in accordance with a signal havingone or more data packets, such as data from one component interactingwith another component in a local system, distributed system, and/oracross a network such as the Internet with other systems by way of thesignal.

Techniques described herein may be used for various wirelesscommunication systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, andother systems. The terms “system” and “network” may often be usedinterchangeably. A CDMA system may implement a radio technology such asCDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000covers IS-2000, IS-95, and IS-856 standards. IS-2000 Releases 0 and Aare commonly referred to as CDMA2000 1×, 1×, etc. IS-856 (TIA-856) iscommonly referred to as CDMA2000 1×EV-DO, High Rate Packet Data (HRPD),etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. ATDMA system may implement a radio technology such as Global System forMobile Communications (GSM). An OFDMA system may implement a radiotechnology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA),IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM™, etc.UTRA and E-UTRA are part of Universal Mobile Telecommunication System(UMTS). 3GPP Long Term Evolution (LTE), LTE-Advanced (LTE-A) arereleases of UMTS that use E-UTRA. New Radio (NR) is a new release ofUMTS. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documentsfrom an organization named “3rd Generation Partnership Project” (3GPP).CDMA2000 and UMB are described in documents from an organization named“3rd Generation Partnership Project 2” (3GPP2). The techniques describedherein may be used for the systems and radio technologies mentionedabove as well as other systems and radio technologies, includingcellular (e.g., NR or LTE) communications over a shared radio frequencyspectrum band. The techniques described herein are applicable to anynext generation communications systems including 5th Generation (5G)/NRor LTE/LTE-A applications.

The following description provides examples, and is not limiting of thescope, applicability, or examples set forth in the claims. Changes maybe made in the function and arrangement of elements discussed withoutdeparting from the scope of the disclosure. Various examples may omit,substitute, or add various procedures or components as appropriate. Forinstance, the methods described may be performed in an order differentfrom that described, and various steps may be added, omitted, orcombined. Also, features described with respect to some examples may becombined in other examples.

Various aspects or features will be presented in terms of systems thatcan include a number of devices, components, modules, and the like. Itis to be understood and appreciated that the various systems can includeadditional devices, components, modules, etc. and/or may not include allof the devices, components, modules etc. discussed in connection withthe figures. A combination of these approaches can also be used.

FIG. 1 illustrates an example of a wireless communication system 100 inaccordance with various aspects of the present disclosure. The wirelesscommunication system 100 may include one or more base stations 105, oneor more UEs 115, and a core network 130. The core network 130 mayprovide user authentication, access authorization, tracking, internetprotocol (IP) connectivity, and other access, routing, or mobilityfunctions. The base stations 105 may interface with the core network 130through backhaul links 132 (e.g., S1, etc.). The base stations 105 mayperform radio configuration and scheduling for communication with theUEs 115, or may operate under the control of a base station controller(not shown). In various examples, the base stations 105 may communicate,either directly or indirectly (e.g., through core network 130), with oneanother over backhaul links 134 (e.g., X1, etc.), which may be wired orwireless communication links.

The base stations 105 may wirelessly communicate with the UEs 115 viaone or more base station antennas. Each of the base stations 105 mayprovide communication coverage for a respective geographic coverage area110. In some examples, base stations 105 may be referred to as a networkentity, a base transceiver station, a radio base station, an accesspoint, a radio transceiver, a NodeB, eNodeB (eNB), gNodeB (gNB), HomeNodeB, a Home eNodeB, or some other suitable terminology. The geographiccoverage area 110 for a base station 105 may be divided into sectorsmaking up only a portion of the coverage area (not shown). The wirelesscommunication system 100 may include base stations 105 of differenttypes (e.g., macro or small cell base stations). Additionally, theplurality of base stations 105 may operate according to different onesof a plurality of communication technologies (e.g., 5G, fourthgeneration (4G)/LTE, 3G, Wi-Fi, Bluetooth, etc.), and thus there may beoverlapping geographic coverage areas 110 for different technologies.

In some examples, the wireless communication system 100 may be orinclude a Long Term Evolution (LTE) or LTE-Advanced (LTE-A) network. Thewireless communication system 100 may also be a next generation network,such as a 5G wireless communication network. In LTE/LTE-A networks, theterm evolved node B (eNB) may be generally used to describe the basestations 105, while the term UE may be generally used to describe theUEs 115. The wireless communication system 100 may be a heterogeneousLTE/LTE-A network in which different types of eNBs provide coverage forvarious geographical regions. For example, each eNB or base station 105may provide communication coverage for a macro cell, a small cell, orother types of cell. The term “cell” is a 3GPP term that can be used todescribe a base station, a carrier or component carrier associated witha base station, or a coverage area (e.g., sector, etc.) of a carrier orbase station, depending on context.

A macro cell may cover a relatively large geographic area (e.g., severalkilometers in radius) and may allow unrestricted access by UEs 115 withservice subscriptions with the network provider.

A small cell may include a lower-powered base station, as compared witha macro cell, that may operate in the same or different (e.g., licensed,unlicensed, etc.) frequency bands as macro cells. Small cells mayinclude pico cells, femto cells, and micro cells according to variousexamples. A pico cell, for example, may cover a small geographic areaand may allow unrestricted access by UEs 115 with service subscriptionswith the network provider. A femto cell may also cover a smallgeographic area (e.g., a home) and may provide restricted access by UEs115 having an association with the femto cell (e.g., UEs 115 in a closedsubscriber group (CSG), UEs 115 for users in the home, and the like). AneNB for a macro cell may be referred to as a macro eNB. An eNB for asmall cell may be referred to as a small cell eNB, a pico eNB, a femtoeNB, or a home eNB. An eNB may support one or multiple (e.g., two,three, four, and the like) cells (e.g., component carriers).

The communication networks that may accommodate some of the variousdisclosed examples may be packet-based networks that operate accordingto a layered protocol stack and data in the user plane may be based onthe IP. A radio link control (RLC) layer may perform packet segmentationand reassembly to communicate over logical channels. A MAC layer mayperform priority handling and multiplexing of logical channels intotransport channels. The MAC layer may also use hybrid automaticrepeat/request (HARD) to provide retransmission at the MAC layer toimprove link efficiency. In the control plane, the radio resourcecontrol (RRC) protocol layer may provide establishment, configuration,and maintenance of an RRC connection between a UE 115 and the basestations 105. The RRC protocol layer may also be used for core network130 support of radio bearers for the user plane data. At the physical(PHY) layer, the transport channels may be mapped to physical channels.

The UEs 115 may be dispersed throughout the wireless communicationsystem 100, and each UE 115 may be stationary or mobile. A UE 115 mayalso include or be referred to by those skilled in the art as a mobilestation, a subscriber station, a mobile unit, a subscriber unit, awireless unit, a remote unit, a mobile device, a wireless device, awireless communications device, a remote device, a mobile subscriberstation, an access terminal, a mobile terminal, a wireless terminal, aremote terminal, a handset, a user agent, a mobile client, a client, orsome other suitable terminology. A UE 115 may be a cellular phone, apersonal digital assistant (PDA), a wireless modem, a wirelesscommunication device, a handheld device, a tablet computer, a laptopcomputer, a cordless phone, a wireless local loop (WLL) station, anentertainment device, a vehicular component, an appliance, anautomobile, any other suitable “Internet of Things” (IoT) device, or thelike. A UE may be able to communicate with various types of basestations and network equipment including macro eNBs, small cell eNBs,macro gNBs, small cell gNBs, relay base stations, and the like.

The wireless communication links 125 shown in wireless communicationsystem 100 may carry uplink (UL) transmissions from a UE 115 to a basestation 105, or downlink (DL) transmissions, from a base station 105 toa UE 115. The downlink transmissions may also be called forward linktransmissions while the uplink transmissions may also be called reverselink transmissions. Each wireless communication link 125 may include oneor more carriers, where each carrier may be a signal made up of multiplesub-carriers (e.g., waveform signals of different frequencies) modulatedaccording to the various radio technologies described above. Eachmodulated signal may be sent on a different sub-carrier and may carrycontrol information (e.g., reference signals, control channels, etc.),overhead information, user data, etc. The wireless communication links125 may transmit bidirectional communications using frequency divisionduplex (FDD) (e.g., using paired spectrum resources) or time divisionduplex (TDD) operation (e.g., using unpaired spectrum resources). Framestructures may be defined for FDD (e.g., frame structure type 1) and TDD(e.g., frame structure type 2).

In aspects of the wireless communication system 100, base stations 105or UEs 115 may include multiple antennas for employing antenna diversityschemes to improve communication quality and reliability between basestations 105 and UEs 115. Additionally or alternatively, base stations105 or UEs 115 may employ multiple input multiple output (MIMO)techniques that may take advantage of multi-path environments totransmit multiple spatial layers carrying the same or different codeddata.

Wireless communication system 100 may support operation on multiplecells or carriers, a feature which may be referred to as carrieraggregation (CA) or multi-carrier operation. A carrier may also bereferred to as a component carrier (CC), a layer, a channel, etc. Theterms “carrier,” “component carrier,” “cell,” and “channel” may be usedinterchangeably herein. A UE 115 may be configured with multipledownlink CCs and one or more uplink CCs for carrier aggregation. Carrieraggregation may be used with both FDD and TDD component carriers.Moreover, in some aspects, the wireless communication links 135 mayrepresent one or more broadcast channels.

In aspects of the wireless communication system 100, the wirelesscommunication system 100 may have a UE-centric MAC layer and/or forperforming UE-centric or uplink-based mobility. On the network side, thebase stations 105 may broadcast a synchronization signal. Thesynchronization signal may be a unified synchronization signal that issupported by systems using a UE-centric MAC layer (e.g., UECM networks),and/or for performing UE-centric or uplink-based mobility, as well assystems using a network-centric or non UE-centric MAC layer (e.g., nUECMnetworks), and/or for performing network-centric or downlink-basedmobility. The UEs 115 may receive the synchronization signal, acquire atiming of the network from the synchronization signal, and in responseto acquiring the timing of the network, transmit a pilot signal. Thepilot signal transmitted by a UE 115 may be concurrently receivable by aplurality of cells (e.g., base stations) within the network. Each of theplurality of cells may measure a strength of the pilot signal, and thenetwork (e.g., one or more of the base stations 105 and/or a centralnode within the core network 130) may determine a serving cell for theUE 115. As the UE 115 continues to transmit a pilot signal, the networkmay handover the UE 115 from one serving cell to another, with orwithout informing the UE 115. System information may be transmitted toUEs 115 on-demand (e.g., in response to a UE 115 transmitting a pilotsignal), thus enabling the network to forego broadcasting the systeminformation and enabling the network to conserve power.

The synchronization signal transmitted by the base stations 105 beingunified, however, may not identify a given cell, but rather may identify(e.g., by indicating a zone identifier in the signal) a zone of multiplecells operating on the same frequency and/or with the same timing, etc.,as described further herein. There may be instances, however, where a UE115 may benefit from knowing physical cell identifiers of a servingcell, neighboring cell, etc. within (or outside of) the zone.Accordingly, the base stations 105 may also separately transmitcell-specific signals. For example, the base stations 105 may transmitmeasurement reference signals (MRS), which may be scrambled based on aphysical cell identifier. Alternatively or in addition, the basestations 105 may separately transmit cell-specific synchronizationsignals, which may be generated based on a sequence that indicates thephysical cell identifier. UE 115 can receive the cell-specific signalsfrom one or more base stations 105 and identify corresponding cellsbased at least in part on determining the physical cell identifier thatcorresponds to the cell-specific signals (e.g., based on determining anMRS scrambling code, cell-specific synchronization signal sequence,etc.). In another example, the cell determined as the serving cell forthe UE 115, as described above, may transmit the cell-specific signal(e.g., in response to the pilot signal from the UE 115) to facilitateserving cell discovery by the UE 115.

In aspects of the wireless communication system 100, a base station 105may include a cell-specific signal transmitting component 340 (see e.g.,FIG. 3) configured to determine whether to transmit a cell-specificsignal to one or more UEs. The determination can be based at least inpart on determining whether the base station 105 receives a pilot signalfrom the UE 115 at a highest power (e.g., at a highest received signalstrength indicator (RSSI), reference signal received power (RSRP),reference signal received quality (RSRQ), SNR, etc.) compared to otherbase stations 105 (e.g., at a higher power than received by other basestations in the same zone). Thus, in one example, base stations in azone can communicate the power at which the pilot signal is received tocoordinate and determine one (or more) base station(s) as the servingbase station(s) for the UE 115. In another example, base station 105 cantransmit the cell-specific signal in response to the pilot signal fromthe UE 115 or other detected event, in a periodic manner, and/or thelike. In an example, the cell-specific signal transmitting component 340can scramble a MRS based on a physical cell identifier such that the UEcan identify the cell transmitting the MRS. In another example, thecell-specific signal transmitting component 340 can generate acell-specific synchronization signal based on a sequence that indicatesthe physical cell identifier, such that the UE can identify the celltransmitting the cell-specific synchronization signal.

In other aspects of the wireless communication system 100, a UE 115 mayinclude a physical cell identifier discovering component 440 configuredto determine whether to discover a physical cell identifier of one ormore cells, which may be based on a detected event, in a periodicmanner, etc. For example, physical cell identifier discovering component440 may determine to discover a physical cell identifier based onreceiving a positive paging indicator (such as a keep alive message)from the one or more cells, receiving the synchronization signal fromone or more cells in a zone, determining to cancel interference from oneor more neighboring cells, detecting a threshold change insignal-to-noise ratio, determining to perform mobility management, etc.In an example, physical cell identifier discovering component 440 maydetermine physical cell identifiers based on cell-specific signalsreceived from various cells (e.g., from one or more base stations).Alternatively or in addition, physical cell identifier discoveringcomponent 440 may determine a serving physical cell identifier and/ormay determine one or more neighboring physical cell identifiers, asdescribed further herein.

FIG. 2 shows a diagram 200 illustrating a UECM network zone (e.g.,zone_1) having a coverage area 110-a and including at least a cell_1having a coverage area 110-b and a cell_2 having a coverage area 110-c.The UECM network zone may be a zone associated with at least a portionof the wireless communication system 100 described in FIG. 1. A zone,such as zone_1, may refer to a group or combination of cells that acttogether and are highly synchronized (e.g., based on being provided bythe same base station, synchronizing timing between associated basestations over a backhaul link, etc.). Because of the coordinatedoperation of the cells in a zone, the synchronization signals arezone-specific. That is, the synchronization signals transmitted (e.g.,broadcast) from a zone are typically single-frequency network (SFN)synchronization signals. A single-frequency network is a broadcastnetwork where several transmitters simultaneously send the same signalover the same frequency channel.

The use of zones in 5G networks or other next generation communicationsystems may be advantageous for mobility management operations. Forexample, when in a zone, cell reselection may be transparent to a UE.The network may be responsible for cell reselection and mobility, andthe UE can be relieved from those responsibilities. Such an approach maybe efficient for the UE, and also can be efficient for the networkbecause the number of mobility messages that need to be exchanged with aUE may be reduced.

The use of zones in 5G networks or other next generation communicationsystems may also enable certain applications such as massive MIMO, forexample. Massive MIMO, which is also known as Large-Scale AntennaSystems, Very Large MIMO, Hyper MIMO, Full-Dimension MIMO and ARGOS,makes use of a very large number of service antennas (e.g., hundreds orthousands) that are operated fully coherently and adaptively. Extraantennas may help by focusing the transmission and reception of signalenergy into smaller regions improving throughput and energy efficiency,in particularly when combined with simultaneous scheduling of a largenumber of user terminals (e.g., tens or hundreds). Massive MIMO wasoriginally envisioned for time division duplex (TDD) operation, but canpotentially be applied also in frequency division duplex (FDD)operation. Massive MIMO may provide additional benefits, including theuse of inexpensive low-power components, reduced latency, simplificationof the MAC layer, and robustness to interference and intentionaljamming.

Also shown in FIG. 2 is a UE 115 located in an overlapping area orregion between the UECM network zone and an nUECM network cell (e.g.,cell_3 having coverage area 110-d). The nUECM network cell may be a cellassociated with at least a portion of a wireless communication systemhaving a network-centric MAC layer. The UE 115 in the overlapping areamay receive unified synchronization signals from base station 105-a incell_1 of zone_1 and/or from base station 105-b in cell_3. In otherwords, the UE 115 in the overlapping area may receive synchronizationsignals from a UECM network zone (e.g., cell_1 in zone_1) and/or from annUECM network cell (e.g., cell_3). For example, base station 105-a maygenerate and transmit (e.g., broadcast) unified synchronization signals,which may identify zone_1 and/or cell_1, as well as a nominal tonespacing being used by zone_1. Moreover, base station 105-b may transmit(e.g., broadcast) unified synchronization signals, which may identifycell_3.

After receiving the unified synchronization signals, whether from a UECMnetwork zone or an nUECM network cell, the UE 115 in the overlappingarea may process the unified synchronization signals to determinewhether the network transmitting the signals is a UECM network or annUECM network. The UE 115 may also detect, where the network is a UECMnetwork, a nominal numerology (e.g., tone spacing) being used by thenetwork. The UE 115 may detect the nominal numerology based on a numberof copies of the unified synchronization signals received from a UECMnetwork.

As described, however, the unified synchronization signals may identifythe zone, but may not identify the cell from which the signal istransmitted. As such, base station 105-a in cell_1 may also transmit,via a cell-specific signal transmitting component 340 (see e.g., FIG.3), a cell-specific signal 205-a where the cell-specific signal canindicate a physical cell identifier of cell_1.

Similarly, for example, a cell-specific signal 205-b related to cell_2can also be transmitted. For instance, a cell-specific signal 205-brelated to cell_2 can be transmitted from base station 105-a or anotherbase station associated with cell_2 in zone_1 110-a where thecell-specific signal 205-b can indicate a physical cell identifier ofcell_2. For example, the cell-specific signals may include MRSs that arescrambled using a scrambling code that is associated with the physicalcell identifier. In another example, the cell-specific signals mayinclude cell-specific synchronization signals that are generated using asequence (e.g., a binary sequence, m-sequence, Zadoff-Chu sequence,etc.) that is associated with the physical cell identifier.

Accordingly, UE 115 can receive the cell-specific signal(s) 205-a and/or205-b from cell_1 and/or cell_2, and may identify one or more of thecells based on the corresponding cell-specific signal(s). In anotherexample, UE 115 may identify a serving cell as one of cell_1 or cell_2based on a received cell-specific signal, and/or may determine one ormore neighboring physical cell identifiers, as described herein.

Turning now to FIGS. 3-6, aspects are depicted with reference to one ormore components and one or more methods that may perform the actions oroperations described herein, where aspects in dashed line may beoptional. Although the operations described below in FIGS. 5 and 6 arepresented in a particular order and/or as being performed by an examplecomponent, it should be understood that the ordering of the actions andthe components performing the actions may be varied, depending on theimplementation. Moreover, it should be understood that the followingactions, functions, and/or described components may be performed by aspecially-programmed processor, a processor executingspecially-programmed software or computer-readable media, or by anyother combination of a hardware component and/or a software componentcapable of performing the described actions or functions.

Referring to FIG. 3, a block diagram 300 is shown that includes aportion of a wireless communications system having multiple UEs 115 incommunication with a base station 105 via wireless communication links125, where the base station 105 is also connected to a network 310. TheUEs 115 may be examples of the UEs described in the present disclosurethat are configured to receive and process unified synchronizationsignals. Moreover the base station 105 may be an example of the basestations described in the present disclosure that are configured togenerate and transmit cell-specific signals. In an example, the basestation 105 in FIG. 3 may be part of a UECM network and may transmitcell-specific signals that indicate a physical cell identifier.

In an aspect, the base station in FIG. 3 may include one or moreprocessors 305 and/or memory 302 that may operate in combination withcell-specific signal transmitting component 340 to perform thefunctions, methodologies (e.g., method 500 of FIG. 5), or methodspresented in the present disclosure. In accordance with the presentdisclosure, the cell-specific signal transmitting component 340 mayinclude an optional MRS scrambling component 342 configured forscrambling an MRS, an optional signal sequence generating component 344configured for generating a sequence for a cell-specific referencesignal (e.g., a binary sequence), and/or an optional signal measuringcomponent 346 configured for measuring a signal received from UE 115 todetermine whether to transmit the MRS.

The one or more processors 305 may include a modem 320 that uses one ormore modem processors. The various functions related to thecell-specific signal transmitting component 340, and/or itssub-components, may be included in modem 320 and/or processor 305 and,in an aspect, can be executed by a single processor, while in otheraspects, different ones of the functions may be executed by acombination of two or more different processors. For example, in anaspect, the one or more processors 305 may include any one or anycombination of a modem processor, a baseband processor, a digital signalprocessor, a transmit processor, a transceiver processor associated withtransceiver 370, a system-on-chip (SoC), etc. In particular, the one ormore processors 305 may execute functions and components included in thecell-specific signal transmitting component 340.

In some examples, the cell-specific signal transmitting component 340and each of the sub-components may comprise hardware, firmware, and/orsoftware and may be configured to execute code or perform instructionsstored in a memory (e.g., a computer-readable storage medium, such asmemory 302 discussed below). Moreover, in an aspect, the base station105 in FIG. 3 may include a radio frequency (RF) front end 390 andtransceiver 370 for receiving and transmitting radio transmissions to,for example, UEs 115. The transceiver 370 may coordinate with the modem320 to transmit messages generated by the cell-specific signaltransmitting component 340 (e.g., MRSs, cell-specific synchronizationsignals, etc.) to the UEs. RF front end 390 may be connected to one ormore antennas 373 and can include one or more switches 392, one or moreamplifiers (e.g., power amplifiers (PAs) 394 and/or low-noise amplifiers391), one or more filters 393, etc. for transmitting and receiving RFsignals on uplink channels and downlink channels. In an aspect, thecomponents of the RF front end 390 can connect with transceiver 370. Thetransceiver 370 may connect to one or more of modem 320 and processors305.

The transceiver 370 may be configured to transmit (e.g., via transmitter(TX) radio 375) and receive (e.g., via receiver (RX) radio 380) wirelesssignals through antennas 373 via the RF front end 390. In an aspect, thetransceiver 370 may be tuned to operate at specified frequencies suchthat the base station 105 can communicate with, for example, UEs 115. Inan aspect, for example, the modem 320 can configure the transceiver 370to operate at a specified frequency and power level based on theconfiguration of the base station 105 and communication protocol used bythe modem 320.

The base station 105 in FIG. 3 may further include a memory 302, such asfor storing data used herein and/or local versions of applications orcell-specific signal transmitting component 340 and/or one or more ofits sub-components being executed by processor 305. Memory 302 caninclude any type of computer-readable medium usable by a computer orprocessor 305, such as random access memory (RAM), read only memory(ROM), tapes, magnetic discs, optical discs, volatile memory,non-volatile memory, and any combination thereof. In an aspect, forexample, memory 302 may be a computer-readable storage medium thatstores one or more computer-executable codes defining cell-specificsignal transmitting component 340 and/or one or more of itssub-components. Additionally or alternatively, the base station 105 mayinclude a bus 311 for coupling one or more of the RF front end 390, thetransceiver 374, the memory 302, or the processor 305, and to exchangesignaling information between each of the components and/orsub-components of the base station 105.

In an aspect, the processor(s) 305 may correspond to one or more of theprocessors described in connection with the base station in FIG. 8.Similarly, the memory 302 may correspond to the memory described inconnection with the base station in FIG. 8.

Referring to FIG. 4, a block diagram 400 is shown that includes aportion of a wireless communications system having multiple UEs 115 incommunication with a base station 105 via wireless communication links125, where the base station 105 is also connected to a network 310. TheUEs 115 may be examples of the UEs described in the present disclosurethat are configured to receive and process cell-specific signals.Moreover the base station 105 may be an example of the base stationsdescribed in the present disclosure that are configured to generate andtransmit cell-specific signals. In an example, the base station 105 inFIG. 3 may be part of a UECM network or an nUECM network and maytransmit cell-specific signals that identify a related cell.

In an aspect, the UE 115 in FIG. 4 may include one or more processors405 and/or memory 402 that may operate in combination with physical cellidentifier discovering component 440 to perform the functions,methodologies (e.g., method 600 of FIG. 6), or methods presented in thepresent disclosure. In accordance with the present disclosure, thephysical cell identifier discovering component 440 may include acell-specific signal receiving component 442 configured for receivingone or more cell-specific signals, a physical cell identifierdetermining component 444 configured for determining a physical cellidentifier indicated by the one or more cell-specific signals, and/or anoptional serving cell determining component 448 configured fordetermining an identifier of a serving cell serving UE 115. In anexample, physical cell identifier determining component 444 mayoptionally include a table 446 that maps MRS scrambling codes and/orcell-specific synchronization signal sequences to corresponding physicalcell identifiers. For example, table 446 may be stored on memory 402,received in a configuration from one or more network components (e.g.,base station 105 or other base stations), etc. In addition, serving celldetermining component 448 may optionally include a control channeldecoding component 450 configured for decoding a control channelreceived from one or more cells based on a determined physical cellidentifier to identify a serving cell serving the UE 115.

The one or more processors 405 may include a modem 420 that uses one ormore modem processors. The various functions related to the physicalcell identifier discovering component 440, and/or its sub-components,may be included in modem 420 and/or processor 405 and, in an aspect, canbe executed by a single processor, while in other aspects, differentones of the functions may be executed by a combination of two or moredifferent processors. For example, in an aspect, the one or moreprocessors 405 may include any one or any combination of a modemprocessor, a baseband processor, a digital signal processor, a transmitprocessor, a transceiver processor associated with transceiver 470, asystem-on-chip (SoC), etc. In particular, the one or more processors 405may execute functions and components included in the physical cellidentifier discovering component 440.

In some examples, the physical cell identifier discovering component 440and each of the sub-components may comprise hardware, firmware, and/orsoftware and may be configured to execute code or perform instructionsstored in a memory (e.g., a computer-readable storage medium, such asmemory 402 discussed below). Moreover, in an aspect, the UE 115 in FIG.4 may include an RF front end 490 and transceiver 470 for receiving andtransmitting radio transmissions to, for example, base stations 105. Thetransceiver 470 may coordinate with the modem 420 to receivecell-specific signals to be processed by the physical cell identifierdiscovering component 440 (e.g., cell-specific signals 205-a and/or205-b in FIG. 2). RF front end 490 may be connected to one or moreantennas 473 and can include one or more switches 492, one or moreamplifiers (e.g., PAs 494 and/or LNAs 491), and one or more filters 493for transmitting and receiving RF signals on uplink channels anddownlink channels. In an aspect, the components of the RF front end 490can connect with transceiver 470. The transceiver 470 may connect to oneor more of modem 420 and processors 405.

The transceiver 470 may be configured to transmit (e.g., via transmitter(TX) radio 475) and receive (e.g., via receiver (RX) radio 480) wirelesssignals through antennas 473 via the RF front end 490. In an aspect, thetransceiver 470 may be tuned to operate at specified frequencies suchthat the UE 115 can communicate with, for example, base stations 105. Inan aspect, for example, the modem 420 can configure the transceiver 470to operate at a specified frequency and power level based on theconfiguration of the UE 115 and communication protocol used by the modem420.

The UE 115 in FIG. 4 may further include a memory 402, such as forstoring data used herein and/or local versions of applications orphysical cell identifier discovering component 440 and/or one or more ofits sub-components being executed by processor 405. Memory 402 caninclude any type of computer-readable medium usable by a computer orprocessor 405, such as RAM, ROM, tapes, magnetic discs, optical discs,volatile memory, non-volatile memory, and any combination thereof. In anaspect, for example, memory 402 may be a computer-readable storagemedium that stores one or more computer-executable codes definingphysical cell identifier discovering component 440 and/or one or more ofits sub-components. Additionally or alternatively, the UE 115 mayinclude a bus 411 for coupling one or more of the RF front end 490, thetransceiver 474, the memory 402, or the processor 405, and to exchangesignaling information between each of the components and/orsub-components of the UE 115.

In an aspect, the processor(s) 405 may correspond to one or more of theprocessors described in connection with the UE in FIG. 8. Similarly, thememory 402 may correspond to the memory described in connection with theUE in FIG. 8.

FIG. 5 illustrates a flow chart of an example of a method 500 fortransmitting (e.g., from a base station), one or more cell-specificsignals to one or more UEs, where the cell-specific signals can identifya corresponding cell.

At Block 502, method 500 may optionally include transmitting a unifiedsynchronization signal with one or more cells in a zone of cells. In anaspect, transceiver 370, e.g., in conjunction with processor(s) 305and/or memory 302, can transmit the unified synchronization signal withthe one or more cells in the zone of cells. In an aspect, the cells cancommunicate to operate within the zone such as to operate on the samefrequency and/or with the same timing, etc. For example, the cells maysynchronize frequency and/or timing based on being provided by the samebase station. As another example, the cells may synchronize frequencyand/or timing by communicating with base stations providing the cellsvia a backhaul link. The cells may also coordinate transmission of theunified synchronization signal to allow a UE, such as UE 115, to receivethe synchronization signal and accordingly synchronize communicationswith the zone of cells for communicating therewith. In an example, theUE, based on receiving the unified synchronization signal, can transmita pilot signal, chirp signal, etc. for receiving by the zone of cells torequest additional parameters for communicating with the zone of cells.The unified synchronization signal, as described, may indicate anidentifier of the zone but may not indicate an identifier of the cell ofbase station 105 (e.g., and/or one or more of the other cells in thezone) transmitting the synchronization signal.

At Block 504, method 500 includes determining to transmit acell-specific signal based at least in part on detecting a condition. Inan aspect, cell-specific signal transmitting component 340, e.g., inconjunction with processor(s) 305, memory 302, and/or transceiver 370,can determine to transmit a cell-specific signal based at least in parton detecting the condition. For example, the condition may relate toreceiving a request for a cell-specific signal from the UE 115; in thisexample, cell-specific signal transmitting component 340 can receive therequest from the UE 115, which may include a request in a pilot signal.For example, UE 115 may transmit a pilot signal to request on-demandtransmission of cell-specific signals, such as MRS, cell-specificsynchronization signals, system information signals, etc. from basestation 105.

In one example, UE 115 can operate in a radio resource control(RRC)-common state where the UE is camped on a cell of a base station105 but may be inactive and periodically waking up to monitor for pagingsignals from the base station. In another example, UE 115 may discoverthe zone of cells based on receiving a unified synchronization signal.In either state, UE 115 can transmit a pilot signal for the purpose ofrequesting cell-specific signals or other reference signals from thebase station 105 (or for other purposes, such as requesting to performrandom access). For example, the pilot signal may be referred to as achirp signal, which can be sent for a specific purpose where the purposemay be indicated in the chirp signal (e.g., a purpose to requestreference signal, request a random access procedure, request on-demandsystem information, support mobility tracking, etc.). In any case,cell-specific signal transmitting component 340 may determine totransmit the cell-specific signal based on receiving one or more signalsfrom UE 115. In another example, cell-specific signal transmittingcomponent 340 may determine to transmit the cell-specific signal basedon another event and/or periodically based on a configured interval,duration, etc.

In an example, determining to transmit the cell-specific signal at Block504 may optionally include, at Block 506, determining a chirp signalstrength received at a threshold power. In an aspect, signal measuringcomponent 346, e.g., in conjunction with processor(s) 305, memory 302,and/or transceiver 370, can determine the chirp signal strength receivedat a threshold power. For example, signal measuring component 346 candetermine the strength (e.g., RSSI, RSRP, RSRQ, SNR, etc.) of the chirpsignal, as received from UE 115, as achieving a threshold power, wherethe threshold power may be a configured threshold power, a dynamicthreshold power set as a strength at which the chirp signal is receivedat another base station in the zone, etc. Thus, in one example, signalmeasuring component 346 can determine whether the strength of the chirpsignal is strongest at base station 105 (e.g., based on receiving anindication of the strength of the chirp signal at other base stations inthe zone), and if so, cell-specific signal transmitting component 340can determine to transmit the cell-specific signal to the UE 115. Inthis example, base station 105 may determine itself to be the servingcell for the UE, and may be the only base station in the zonetransmitting the cell-specific signal to the UE 115. This can facilitatedetermination of the serving physical cell identifier at the UE 115based on receiving the cell-specific signal and identifying the physicalcell identifier associated therewith. In another example, signalmeasuring component 346 can determine that the strength of the chirpsignal is strong enough for the base station 105 to be considered aneighboring cell of a serving cell of the UE 115, and cell-specificsignal transmitting component 340 can accordingly transmit acell-specific signal.

In one example, cell-specific signal transmitting component 340 candetermine to transmit a cell-specific signal based on one or morecommands received from other cells/base stations or other networkcomponents. In this example, the other network components may determinewhich cell is to be the serving cell and which cells are to beneighboring cells based on the signal strength of the chirp signal asreceived at the cells. For example, a set of cells can be determined ascells at which the chirp signal is received at least at a thresholdpower. The cell in the set of the cells at which the chirp signal isstrongest can be considered the serving cell, and the other cells can beconsidered neighboring cells. In an example, the cells can communicatethe power of the chirp signal as received from the UE 115 (e.g., basedon determining that the chirp signal is received) and can accordinglydetermine the serving cell and/or one or more neighboring cells for theUE 115 based on determining whether a given cell received the chirpsignal at a highest power among the communicating cells.

The cells/base stations or other network components can accordinglycause the serving cell and/or the neighboring cells to sendcell-specific signals. In one example, this may be based on receivingthe chirp signal from the wireless device (which may specify to transmitthe cell-specific signals). As described further herein, the wirelessdevice (e.g., UE 115) may detect a positive paging indicator from theserving cell (e.g., based on the serving cell transmitting acell-specific signal, as described further herein), and can accordinglytrigger a neighbor physical cell identifier search procedure to discoverneighboring physical cell identifiers based on receiving subsequentlytransmitted cell-specific signals from the cells determined to beneighboring cells.

Method 500 may also include, at Block 510, associating the cell-specificsignal to a physical cell identifier. In an aspect, cell-specific signaltransmitting component 340, or one or more components thereof, e.g., inconjunction with processor(s) 305, memory 302, and/or transceiver 370,can associate the cell-specific signal to the physical cell identifierto allow a device receiving the cell-specific signal to determine theidentifier based on one or more properties of the cell-specific signal.For example, associating the cell-specific signal to the physical cellidentifier at Block 510 may optionally include, at Block 512, scramblingthe MRS based on a physical cell identifier. In an aspect, MRSscrambling component 342, e.g., in conjunction with processor(s) 305,memory 302, and/or transceiver 370, can scramble the MRS based on thephysical cell identifier. For example, MRS scrambling component 342 canscramble the MRS using a scrambling code correlated to a physical cellidentifier of a cell of base station 105. For example, the scramblingcodes and physical cell identifiers may be associated in a table, asdescribed above, which can be configured in the base station 105 (e.g.,as stored in a memory 302 thereof). In another example, MRS scramblingcomponent 342 can scramble the MRS using a scrambling code that iscomputed or otherwise pseudo-randomly determined based on the physicalcell identifier (e.g., according to a function or formula configured atthe base station 105). In any case, a device receiving the cell-specificsignal can include or can be configured with information for determiningthe scrambling code and the associated physical cell identifier, asdescribed further herein.

In another example, associating the cell-specific signal to the physicalcell identifier, at Block 510, may optionally include, at Block 514,generating a sequence for the cell-specific signal based on a physicalcell identifier. In an aspect, signal sequence generating component 344,e.g., in conjunction with processor(s) 305, memory 302, and/ortransceiver 370, may generate the sequence for the cell-specific signal(e.g., the cell-specific synchronization signal, the MRS, etc.) based onthe physical cell identifier. For example, signal sequence generatingcomponent 344 can generate the sequence as a binary sequence, anm-sequence, where m is a positive integer, a Zadoff-Chu sequence, othersequences with good cross-correlation properties, etc. to indicate thephysical cell identifier. For example, the sequences and physical cellidentifiers may be associated in a table, as described above, which canbe configured in the base station 105 (e.g., as stored in a memory 302thereof). In another example, signal sequence generating component 344may compute or otherwise pseudo-randomly determine the sequence based onthe physical cell identifier (e.g., according to a formula or functionconfigured at the base station 105). The sequence can be of a specifiedlength that allows for indicating a desired number of possible physicalcell identifiers (e.g., length n to indicate 2^(n) physical cellidentifiers in the case of a binary sequence). In this example, a devicereceiving the cell-specific signal can include or can be configured withinstructions to appropriately decode the sequence of the cell-specificsignal to determine the physical cell identifier.

Method 500 can also include, at Block 516, transmitting thecell-specific signal as part of operating in the zone of cells. In anaspect, cell-specific signal transmitting component 340, e.g., inconjunction with processor(s) 305, memory 302, and/or transceiver 370,can transmit the cell-specific signal as part of operating in the zoneof cells. In this regard, for example, cell-specific signal transmittingcomponent 340 can transmit the cell-specific signal to UE 115, which mayoccur without cell-specific signals transmitted from other cells in thezone (e.g., where signal measuring component 346 determines a strengthof a signal received from the UE 115 achieves a threshold). In anotherexample, cell-specific signal transmitting component 340 can transmitthe cell-specific signal to UE 115 along with other base stations/cellstransmitting cell-specific signals, where the cell-specific signalstransmitted by the other base stations may be transmitted as, forexample, MRSs scrambled with different scrambling codes corresponding todifferent physical cell identifiers, cell-specific synchronizationsignals generated with different sequences corresponding to differentphysical cell identifiers, etc. Accordingly, UE 115 can receive thecell-specific signal(s) and determine physical cell identifierscorresponding to the cells for various purposes (e.g., to communicatewith the cell, perform interference cancellation, determine SNR ofneighboring cells, perform mobility management, etc.).

In one example, cell-specific signal transmitting component 340 cantransmit the cell-specific signal as a cell-specific synchronizationsignal over a similar bandwidth used to transmit unified synchronizationsignals for the zone. An example is depicted in FIG. 7, whichillustrates an example of a bandwidth 700 that can be allocated by oneor more cells. For example, bandwidth 700 can include a plurality ofsymbols (e.g., OFDM symbols, SC-FDM symbols, etc.) corresponding to aperiod of time (e.g., a portion of a subframe, etc.). Bandwidth 700includes a plurality of symbols allocated for a downlink burst 702, aplurality of symbols for a physical downlink shared channel (PDSCH)region 704, a guard period (GP) symbol 706, and a symbol allocated foran uplink burst 708. In this example, base station 105 can transmit aprimary synchronization signal (PSS) 710, primary broadcast channel(PBCH) 712, secondary synchronization signal (SSS) 714, PBCH 716, etc.in one or more symbols in the PDSCH region 704, where the PSS 710, PBCH712, SSS 714, and PBCH 716 may be unified and similarly transmitted bymultiple base stations/cells in a zone.

In this example, cell-specific signal transmitting component 340 canalso transmit a cell-specific SSS (SSS-C) 718, which can be generatedusing a sequence to indicate a physical cell identifier as described, ina similar portion of frequency of bandwidth 700 (e.g., 5 megahertz) usedto transmit the unified PSS 710, PBCH 712, SSS 714, and/or PBCH 716.Moreover, in an example, cell-specific signal transmitting component 340may transmit the SSS-C 718 adjacent in time (e.g., in an adjacentsymbol) to one or more of the unified PSS 710, PBCH 712, SSS 714, and/orPBCH 716 (e.g., as part of a synchronization burst that includes unifiedPSS 710, PBCH 712, SSS 714, and/or PBCH 716). In another example,cell-specific signal transmitting component 340 may also transmit acell-specific PBCH (PBCH-C) 720 in a similar portion of frequency ofbandwidth 700 used to transmit the unified PSS 710, PBCH 712, SSS 714,and/or PBCH 716, the SSS-C 718, etc. (e.g., as part of a synchronizationburst that includes unified PSS 710, PBCH 712, SSS 714, and/or PBCH 716,SSS-C 718, etc.). In an example, cell-specific signal transmittingcomponent 340 may transmit the PBCH-C 720 adjacent in time (e.g., in anadjacent symbol) to the SSS-C 718 or one or more of the unified PSS 710,PBCH 712, SSS 714, and/or PBCH 716.

Referring back to FIG. 5, method 500 may also optionally include, atBlock 518, transmitting neighboring physical cell identifiers in asystem information signal. In an aspect, transceiver 370, e.g., inconjunction with processor(s) 305 and/or memory 302, can transmitneighboring physical cell identifiers in a system information signal.For example, UE 115 can communicate with the base station in aRRC-dedicated state as well (e.g., after sending the chirp signal and/orreceiving resources for communicating with the base station).Transceiver 370 can transmit additional signals to the UE 115, such assystem information signals to indicate system information for furthercommunications with the base station 105 (e.g., master informationblocks (MIB), system information blocks (SIB), etc.), which may includea list of neighboring physical cell identifiers. The furthercommunications may include any suitable communications such as, forexample, control channel communications (e.g., PDCCH), shared datachannel communications, (e.g., PDSCH, etc.), and/or the like. Asdescribed, base station 105 and/or one or more related networkcomponents can determine a set of neighboring cells for the UE 115 basedon a strength of the chirp signal as received at each of the cells. UE115 can accordingly utilize the neighboring physical cell identifierinformation for one or more purposes (e.g., to perform interferencecancellation, mobility management, etc.). In an example, the UE 115 canutilize the neighboring physical cell identifier information todetermine the cells that the UE can attempt to discover henceforth,which may include one or more cells in the same zone as the servingcell. Thus, the UE need not continue searching for the cells (e.g., inthe zone).

FIG. 6 illustrates a flow chart of an example of a method 600 fordetermining (e.g., by a UE) one or more physical cell identifiersassociated with one or more received cell-specific signals.

At Block 602, method 600 includes determining to discover a physicalcell identifier of one or more cells in a zone based at least in part ondetecting a condition. In an aspect, physical cell identifierdiscovering component 440, e.g., in conjunction with processor(s) 405,memory 402, and/or transceiver 470, can determine to discover a physicalcell identifier of one or more cells in a zone based at least in part ondetecting a condition. For example, the condition may correspond toreceiving one or more signals from one or more base stations, such as aunified synchronization signal, a keep alive message, and/or the like,determining to cancel interference from one or more neighboring cells,detecting a threshold change in SNR (e.g., SNR with a serving cell fallsbelow a threshold), determining to perform mobility management, etc.Based on detecting the condition, physical cell identifier discoveringcomponent 440 can determine to attempt to receive one or morecell-specific signals, for example. Physical cell identifier discoveringcomponent 440 may also determine to discover the physical cellidentifier based on acquiring synchronization with the zone, in anexample, such that a timing for receiving the cell-specific signals canbe determined based on the acquired synchronization. As another example,the physical cell identifier discovering component 440 may determine todiscover the physical cell identifier based on acquiring synchronizationwith the zone such that a request for the cell-specific signals can betransmitted based on the acquired synchronization.

In this regard, method 600 may also optionally include, at Block 604,transmitting a signal to the one or more cells in the zone. In anaspect, physical cell identifier discovering component 440, e.g., inconjunction with processor(s) 405, memory 402, and/or transceiver 470,can transmit the signal to the one or more cells in the zone to causetransmission of one or more cell-specific signals by one or more basestations, as described above. For example, physical cell identifierdiscovering component 440 may transmit the signal based on detecting thecondition, as described above. In an example, the signal can be a chirpsignal that can indicate a purpose of the signal as being to causetransmission of cell-specific signals (e.g., specifically transmissionof MRS or cell-specific synchronization signals or otherwise) by one ormore base stations in the zone. In another example, the chirp signal mayindicate other purposes (e.g., to perform random access with the basestation 105). Accordingly, one or more base stations receiving thesignal can transmit a cell-specific signal, which may include, forexample, all base stations that receive the chirp signal, all basestations in a zone, the base station in the zone determined to receivethe chirp signal at a highest signal strength among a plurality of basestations receiving the chirp signal (and thus may be considered theserving cell for the UE 115), etc.

Method 600 may also include, at Block 606, receiving a cell-specificsignal from at least one of the one or more cells in the zone. In anaspect, cell-specific signal receiving component 442, e.g., inconjunction with processor(s) 405, memory 402, and/or transceiver 470,can receive the cell-specific signal from at least one of the one ormore cells in the zone. For example, cell-specific signal receivingcomponent 442 may receive a cell-specific signal from base station 105,which may indicate a physical cell identifier corresponding to the basestation 105 and/or related cell. For example, as described, thecell-specific signal may be, for instance, a MRS scrambled signal basedon the physical cell identifier of base station 105, a cell-specificsynchronization signal generated based on a sequence corresponding tothe physical cell identifier of base station 105, etc. In addition,cell-specific signal receiving component 442 may receive onecell-specific signal from a determined serving cell in the zone and/ormay receive multiple cell-specific signals from multiple base stations(or related cells) in the zone. As described, in an example,cell-specific signal receiving component 442 may receive thecell-specific signal(s) in response to the signal transmitted byphysical cell identifier discovering component 440 or may receive thecell-specific signal(s) periodically, etc. For instance, cell-specificsignal receiving component 442 can open a measurement gap for receivingone or more cell-specific signals based on transmitting the signal toone or more base stations in the zone. As shown in FIG. 7, in oneexample, cell-specific signal receiving component 442 may receive acell-specific synchronization signal as a SSS-C 718 transmitted using asimilar portion of bandwidth 700 used for transmitting unified PSS 710,PBCH 712, SSS 714, and/or PBCH 716, PBCH-C 720, etc. (e.g., where SSS-Cis transmitted as part of a synchronization burst that includes unifiedPSS 710, PBCH 712, SSS 714, and/or PBCH 716, PBCH-C 720, and/or thelike).

Referring back to FIG. 6, method 600 may also include, at Block 608,associating the cell-specific signal with one of a plurality ofcell-specific hypotheses. In an aspect, physical cell identifierdetermining component 444, e.g., in conjunction with processor(s) 405,memory 402, and/or transceiver 470, can associate the cell-specificsignal with one of the plurality of cell-specific hypotheses. Forexample, the plurality of cell-specific hypotheses may include aplurality of possible scrambling codes for MRSs, which can each beassociated to a physical cell identifier. In another example, theplurality of cell-specific hypotheses may include a plurality ofpossible sequences of cell-specific synchronization signals, which caneach be associated to a physical cell identifier.

Accordingly, associating the cell-specific signal at Block 608 mayoptionally include, at Block 610, associating a MRS with a scramblingcode hypothesis, or, at Block 612, associating a cell-specific signalwith a sequence hypothesis. In either case, for example, physical cellidentifier determining component 444, e.g., in conjunction withprocessor(s) 405, memory 402, and/or transceiver 470, can associate theMRS with the scrambling code hypothesis or the cell-specific signal(e.g., the cell-specific synchronization signal or the MRS), which canbe based at least in part on determining a scrambling code or sequencethat most closely correlates with the received cell-specific signal. Inone example, physical cell identifier determining component 444 cancompare the received cell-specific signal to each of the cell-specifichypotheses (e.g., the scrambling codes or sequences) to determine thehypothesis (e.g., the scrambling code or sequence) to which thecell-specific signal most closely corresponds.

For example, physical cell identifier determining component 444 candecode a MRS using correlation, energy detection, etc. For example,physical cell identifier determining component 444 can detect peaks inthe received bandwidth as MRSs, and can determine the peaks to bepotential cell-specific signals. In another example, physical cellidentifier determining component 444 can similarly decode acell-specific signal (e.g., the cell-specific synchronization signal,MRS, etc.) using correlation, energy detection, etc.

Method 600 may also include, at Block 614, determining the physical cellidentifier that corresponds to the cell-specific hypothesis. In anaspect, physical cell identifier determining component 444, e.g., inconjunction with processor(s) 405, memory 402, and/or transceiver 470,can determine the physical cell identifier that corresponds to thecell-specific hypothesis. For example, physical cell identifierdetermining component 444 may store a mapping of the cell-specifichypotheses to corresponding identifiers in a table 446, which may beconfigured in the UE 115 (e.g., stored in a memory 402, such as a memorychip, subscriber identity module, etc.). In another example, physicalcell identifier determining component 444 may store a function orformula to compute or otherwise pseudo-randomly determine the physicalcell identifier for a determined cell-specific hypothesis. In eithercase, physical cell identifier determining component 444 can determinethe physical cell identifier from the table 446 or based on computingthe physical cell identifier that is associated with the cell-specifichypothesis (e.g., the scrambling code or sequence of the receivedcell-specific signal). In addition, physical cell identifier determiningcomponent 444 may similarly determine physical cell identifiers for oneor more additionally received cell-specific signals. In an example,physical cell identifier determining component 444 may also determine orverify the physical cell identifier based on attempting to decode acell-specific channel using the physical cell identifier (e.g., a PDCCH,PBCH (e.g., PBCH-C 720), etc.

In one example, determining the physical cell identifier at Block 614may optionally include, at Block 616, determining the physical cellidentifier as the serving physical cell identifier. In an aspect,serving cell determining component 448, e.g., in conjunction withprocessor(s) 405, memory 402, and/or transceiver 470, can determine thephysical cell identifier as the serving physical cell identifier. In oneexample, cell-specific signal receiving component 442 may receive onecell-specific signal (e.g., from the cell determined to receive a chirpmessage from UE 115 at the strongest power), and serving celldetermining component 448 can determine the associated cell (identifiedby the physical cell identifier determining component 444) as theserving cell. In another example, serving cell determining component 448may determine the serving cell as the cell from which the cell-specificsignal is received at a highest signal power (e.g., RSSI, RSRP, RSRQ,SNR, etc.), and physical cell identifier determining component 444 candetermine the associated physical cell identifier, as described above.In any case, UE 115 can utilize the serving physical cell identifier forvarious purposes, such as to decode a corresponding communicationschannel (e.g., control channel) from the base station 105. In oneexample, determining the physical cell identifier as the servingphysical cell identifier may cause the cell-specific signal receivingcomponent 442 to detect the cell-specific signal as a positive pagingindicator, and cell-specific signal receiving component 442 mayaccordingly trigger a neighboring physical cell identifier searchprocedure to receive additional cell-specific signals from neighboringcells and/or a request for neighboring physical cell identifiers fromthe serving cell, as described further herein.

In another example, determining the physical cell identifier at Block614 may optionally include, at Block 618, determining one or moreneighboring physical cell identifiers. In an aspect, physical cellidentifier determining component 444, e.g., in conjunction withprocessor(s) 405, memory 402, and/or transceiver 470, can determine theone or more neighboring physical cell identifiers. For example, physicalcell identifier determining component 444 can determine physical cellidentifiers for multiple cell-specific signals that are not determinedto be serving physical cell identifiers as neighboring physical cellidentifiers. In an example, UE 115 can utilize the neighboring physicalcell identifiers (e.g., in conjunction with the serving physical cellidentifier or otherwise) to perform additional functions, such asinterference cancellation, determination of SNR of neighboring cells(e.g., to evaluate the cells for handover), mobility management, etc.

In a specific example, cell-specific signal receiving component 442 mayreceive and measure a plurality of cell-specific signals from aplurality of cells in a zone, and physical cell identifier determiningcomponent 444 may associate the cell-specific signals with associatedphysical cell identifiers, as described. In this example, cell-specificsignal receiving component 442 may also compute an energy for eachcell-specific signal at an output of the RF front end 490, RX radio 480,etc. (e.g., at a correlator output), and may compare the detected energyto a threshold to mitigate the occurrence of false alarm signals (e.g.,signals that are not MRSs and/or not from the zone). For example, thethreshold may be set based on a history of receiving the signals anddetermining whether the signals correspond to any of the MRS scramblingcodes or sequences in the table 446. Accordingly, the threshold may beset to achieve a certain false alarm rate (e.g., 1%, 2%, etc.) balancedwith mitigating incorrectly determining an actual cell-specific signalas a false alarm. In any case, physical cell identifier determiningcomponent 444 can create a list of physical cell identifierscorresponding to cell-specific signals that achieve the threshold energyas the list of neighboring physical cell identifiers.

Method 600 may also optionally include, at Block 620, determining aserving physical cell identifier based on decoding a received controlchannel using the physical cell identifier or one or more other physicalcell identifiers. In an aspect, control channel decoding component 450e.g., in conjunction with processor(s) 405, memory 402, and/ortransceiver 470, can determine the serving physical cell identifierbased on decoding the received control channel using the physical cellidentifier or one or more other physical cell identifiers. For example,control channel decoding component 450 can attempt to decode a controland/or data channel (e.g., PDCCH, PDSCH, PBCH-C 720, etc.) received frombase station 105 or another base station starting with a physical cellidentifier corresponding to the cell-specific signal received at thehighest signal power. If the decoding fails, control channel decodingcomponent 450 can attempt to decode the control channel with a physicalcell identifier corresponding to the cell-specific signal received atthe next highest signal power, and so on until the control channel issuccessfully decoded. Where the decoding succeeds, serving celldetermining component 448 can determine the serving physical cellidentifier as the physical cell identifier that results in successfuldecoding of the control channel, and may cease the serving celldiscovery process. As described, for example, UE 115 may initiate otherprocesses based on determining the serving physical cell identifier,such as a neighboring cell discovery process, a request for a list ofneighboring cells, etc.

Method 600 may also optionally include, at Block 622, receivingneighboring physical cell identifiers in a system information signal. Inan aspect, physical cell identifier discovering component 440, e.g., inconjunction with processor(s) 405, memory 402, and/or transceiver 470,can receive neighboring physical cell identifiers in a systeminformation signal. As described, base station 105 may transmit thesystem information signal as part of RRC-dedicated signaling, controlchannel or shared data channel signaling, etc., once UE 115 establishesa connection with base station 105 (e.g. as its serving cell). Moreover,in an example, physical cell identifier determining component 444 maytransmit a request for the neighboring physical cell identifiers to thedetermined serving cell.

FIG. 8 is a block diagram of a MIMO communication system 800 including abase station 105 and a UE 115. The MIMO communication system 800 mayillustrate aspects of the wireless communication system 100 and diagram200 described with reference to FIGS. 1 and 2. The base station 105 maybe an example of aspects of the base station 105 described withreference to FIGS. 1, 2, and 3. The base station 105 may be equippedwith antennas 834 and 835, and the UE 115 may be equipped with antennas852 and 853. In the MIMO communication system 800, the base station 105may be able to send data over multiple communication links at the sametime. Each communication link may be called a “layer” and the “rank” ofthe communication link may indicate the number of layers used forcommunication. For example, in a 2×2 MIMO communication system wherebase station 105 transmits two “layers,” the rank of the communicationlink between the base station 105 and the UE 115 is two.

At the base station 105, a transmit (Tx) processor 820 may receive datafrom a data source. The transmit processor 820 may process the data. Thetransmit processor 820 may also generate control symbols or referencesymbols. A transmit MIMO processor 830 may perform spatial processing(e.g., precoding) on data symbols, control symbols, or referencesymbols, if applicable, and may provide output symbol streams to thetransmit modulator/demodulators 832 and 833. Each modulator/demodulator832 through 833 may process a respective output symbol stream (e.g., forOFDM, etc.) to obtain an output sample stream. Eachmodulator/demodulator 832 through 833 may further process (e.g., convertto analog, amplify, filter, and upconvert) the output sample stream toobtain a DL signal. In one example, DL signals frommodulator/demodulators 832 and 833 may be transmitted via the antennas834 and 835, respectively.

The UE 115 may be an example of aspects of the UEs 115 described withreference to FIGS. 1, 2, and 4. At the UE 115, the UE antennas 852 and853 may receive the DL signals from the base station 105 and may providethe received signals to the modulator/demodulators 854 and 855,respectively. Each modulator/demodulator 854 through 855 may condition(e.g., filter, amplify, downconvert, and digitize) a respective receivedsignal to obtain input samples. Each modulator/demodulator 854 through855 may further process the input samples (e.g., for OFDM, etc.) toobtain received symbols. A MIMO detector 856 may obtain received symbolsfrom the modulator/demodulators 854 and 855, perform MIMO detection onthe received symbols, if applicable, and provide detected symbols. Areceive (Rx) processor 858 may process (e.g., demodulate, deinterleave,and decode) the detected symbols, providing decoded data for the UE 115to a data output, and provide decoded control information to a processor880, or memory 882.

The processor 880 may in some cases execute stored instructions toinstantiate a physical cell identifier discovering component 440 (seee.g., FIGS. 1, 2, and 4).

On the uplink (UL), at the UE 115, a transmit processor 864 may receiveand process data from a data source. The transmit processor 864 may alsogenerate reference symbols for a reference signal. The symbols from thetransmit processor 864 may be precoded by a transmit MIMO processor 866if applicable, further processed by the modulator/demodulators 854 and855 (e.g., for SC-FDMA, etc.), and be transmitted to the base station105 in accordance with the communication parameters received from thebase station 105. At the base station 105, the UL signals from the UE115 may be received by the antennas 834 and 835, processed by themodulator/demodulators 832 and 833, detected by a MIMO detector 836 ifapplicable, and further processed by a receive processor 838. Thereceive processor 838 may provide decoded data to a data output and tothe processor 840 or memory 842.

The processor 840 may in some cases execute stored instructions toinstantiate a cell-specific signal transmitting component 340 (see e.g.,FIGS. 1, 2, and 3).

The components of the UE 115 may, individually or collectively, beimplemented with one or more ASICs adapted to perform some or all of theapplicable functions in hardware. Each of the noted modules may be ameans for performing one or more functions related to operation of theMIMO communication system 800. Similarly, the components of the basestation 105 may, individually or collectively, be implemented with oneor more ASICs adapted to perform some or all of the applicable functionsin hardware. Each of the noted components may be a means for performingone or more functions related to operation of the MIMO communicationsystem 800.

The above detailed description set forth above in connection with theappended drawings describes examples and does not represent the onlyexamples that may be implemented or that are within the scope of theclaims. The term “example,” when used in this description, means“serving as an example, instance, or illustration,” and not “preferred”or “advantageous over other examples.” The detailed description includesspecific details for the purpose of providing an understanding of thedescribed techniques. These techniques, however, may be practicedwithout these specific details. In some instances, well-known structuresand apparatuses are shown in block diagram form in order to avoidobscuring the concepts of the described examples.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the above description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, computer-executable code or instructionsstored on a computer-readable medium, or any combination thereof.

The various illustrative blocks and components described in connectionwith the disclosure herein may be implemented or performed with aspecially-programmed device, such as but not limited to a processor, adigital signal processor (DSP), an ASIC, a FPGA or other programmablelogic device, a discrete gate or transistor logic, a discrete hardwarecomponent, or any combination thereof designed to perform the functionsdescribed herein. A specially-programmed processor may be amicroprocessor, but in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aspecially-programmed processor may also be implemented as a combinationof computing devices, e.g., a combination of a DSP and a microprocessor,multiple microprocessors, one or more microprocessors in conjunctionwith a DSP core, or any other such configuration.

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on anon-transitory computer-readable medium. Other examples andimplementations are within the scope and spirit of the disclosure andappended claims. For example, due to the nature of software, functionsdescribed above can be implemented using software executed by aspecially programmed processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations. Also, as used herein, including in the claims, “or” as usedin a list of items prefaced by “at least one of” indicates a disjunctivelist such that, for example, a list of “at least one of A, B, or C”means A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage medium may be anyavailable medium that can be accessed by a general purpose or specialpurpose computer. By way of example, and not limitation,computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to carry or store desiredprogram code means in the form of instructions or data structures andthat can be accessed by a general-purpose or special-purpose computer,or a general-purpose or special-purpose processor. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,include compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofcomputer-readable media.

The previous description of the disclosure is provided to enable aperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the common principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Furthermore, although elements of the describedaspects and/or embodiments may be described or claimed in the singular,the plural is contemplated unless limitation to the singular isexplicitly stated. Additionally, all or a portion of any aspect and/orembodiment may be utilized with all or a portion of any other aspectand/or embodiment, unless stated otherwise. Thus, the disclosure is notto be limited to the examples and designs described herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A method for wireless communications, comprising:receiving, in a portion of bandwidth, a unified synchronization signalfrom one or more cells in a zone, wherein the unified synchronizationsignal identifies the zone, which includes multiple cells; andreceiving, in the portion of bandwidth, a cell-specific signal from acell of the one or more cells in the zone, wherein the cell-specificsignal identifies the cell.
 2. The method of claim 1, wherein receivingthe unified synchronization signal and receiving the cell-specificsignal includes receiving a synchronization burst from the cell, whereinthe synchronization burst includes the unified synchronization signaland the cell-specific signal.
 3. The method of claim 2, whereinreceiving the synchronization burst comprises receiving thesynchronization burst in one or more symbols of a physical downlinkshared channel region.
 4. The method of claim 3, further comprisingtransmitting an uplink burst following a guard period after the physicaldownlink shared channel region.
 5. The method of claim 1, wherein thecell-specific signal includes one or more of a secondary synchronizationsignal (SSS) or a physical broadcast channel (PBCH) specific to thecell.
 6. The method of claim 5, wherein the unified synchronizationsignal includes one or more of a primary synchronization signal (PSS),SSS, or PBCH corresponding to the one or more cells in the zone.
 7. Themethod of claim 1, further comprising: associating the cell-specificsignal with one of a plurality of possible scrambling codes orsequences; and determining a physical cell identifier of the cell as oneof a plurality of physical cell identifiers that corresponds to the oneof the plurality of possible scrambling codes or sequences.
 8. Themethod of claim 1, further comprising determining a serving cell basedon a physical cell identifier corresponding to the cell-specific signal,wherein the cell-specific signal is determined to be a strongestcell-specific signal of a plurality of received cell-specific signals.9. The method of claim 8, further comprising receiving an indication ofone or more neighboring physical cell identifiers from the serving cell.10. The method of claim 9, further comprising determining one or morecells to discover based at least in part on the indication of the one ormore neighboring physical cell identifiers.
 11. An apparatus forwireless communications, comprising: a transceiver for transmitting orreceiving one or more signals via one or more antennas; a memoryconfigured to store instructions; and a processor coupled to thetransceiver and the memory, the processor being configured to executethe instructions to: receive, in a portion of bandwidth, a unifiedsynchronization signal from one or more cells in a zone, wherein theunified synchronization signal identifies the zone, which includesmultiple cells; and receive, in the portion of bandwidth, acell-specific signal from a cell of the one or more cells in the zone,wherein the cell-specific signal identifies the cell.
 12. The apparatusof claim 11, the processor being configured to execute the instructionsto receive the unified synchronization signal and receive thecell-specific signal at least in part by receiving a synchronizationburst from the cell, wherein the synchronization burst includes theunified synchronization signal and the cell-specific signal.
 13. Theapparatus of claim 12, the processor being further configured to executethe instructions to receive the synchronization burst in one or moresymbols of a physical downlink shared channel region.
 14. The apparatusof claim 13, the processor being further configured to execute theinstructions to transmit transmitting an uplink burst following a guardperiod after the physical downlink shared channel region.
 15. Theapparatus of claim 12, wherein the cell-specific signal includes one ormore of a secondary synchronization signal (SSS) or a physical broadcastchannel (PBCH) specific to the cell.
 16. The apparatus of claim 15,wherein the unified synchronization signal includes one or more of aprimary synchronization signal (PSS), SSS, or PBCH corresponding to theone or more cells in the zone.
 17. The apparatus of claim 11, theprocessor being further configured to execute the instructions to:associate the cell-specific signal with one of a plurality of possiblescrambling codes or sequences; and determine a physical cell identifierof the cell as one of a plurality of physical cell identifiers thatcorresponds to the one of the plurality of possible scrambling codes orsequences.
 18. The apparatus of claim 11, the processor being furtherconfigured to execute the instructions to determine a serving cell basedon a physical cell identifier corresponding to the cell-specific signal,wherein the cell-specific signal is determined to be a strongestcell-specific signal of a plurality of received cell-specific signals.19. The apparatus of claim 18, the processor being further configured toexecute the instructions to receive an indication of one or moreneighboring physical cell identifiers from the serving cell.
 20. Theapparatus of claim 19, the processor being further configured to executethe instructions to determine one or more cells to discover based atleast in part on the indication of the one or more neighboring physicalcell identifiers.
 21. An apparatus for wireless communications,comprising: means for receiving, in a portion of bandwidth, a unifiedsynchronization signal from one or more cells in a zone, wherein theunified synchronization signal identifies the zone, which includesmultiple cells; and means for receiving, in the portion of bandwidth, acell-specific signal from a cell of the one or more cells in the zone,wherein the cell-specific signal identifies the cell.
 22. The apparatusof claim 21, wherein the means for receiving the unified synchronizationsignal and the means for receiving the cell-specific signal receive asynchronization burst from the cell, wherein the synchronization burstincludes the unified synchronization signal and the cell-specificsignal.
 23. The apparatus of claim 22, wherein the means for receivingthe synchronization burst receives the synchronization burst in one ormore symbols of a physical downlink shared channel region.
 24. Theapparatus of claim 23, further comprising means for transmitting anuplink burst following a guard period after the physical downlink sharedchannel region.
 25. The apparatus of claim 21, wherein the cell-specificsignal includes one or more of a secondary synchronization signal (SSS)or a physical broadcast channel (PBCH) specific to the cell, and whereinthe unified synchronization signal includes one or more of a primarysynchronization signal (PSS), SSS, or PBCH corresponding to the one ormore cells in the zone.
 26. A non-transitory computer-readable medium,comprising code executable by one or more processors for wirelesscommunication, the code comprising code for: receiving, in a portion ofbandwidth, a unified synchronization signal from one or more cells in azone, wherein the unified synchronization signal identifies the zone,which includes multiple cells; and receiving, in the portion ofbandwidth, a cell-specific signal from a cell of the one or more cellsin the zone, wherein the cell-specific signal identifies the cell. 27.The non-transitory computer-readable medium of claim 26, wherein thecode for receiving the unified synchronization signal and the code forreceiving the cell-specific signal receive a synchronization burst fromthe cell, wherein the synchronization burst includes the unifiedsynchronization signal and the cell-specific signal.
 28. Thenon-transitory computer-readable medium of claim 27, wherein the codefor receiving the synchronization burst receives the synchronizationburst in one or more symbols of a physical downlink shared channelregion.
 29. The non-transitory computer-readable medium of claim 28,further comprising code for transmitting an uplink burst following aguard period after the physical downlink shared channel region.
 30. Thenon-transitory computer-readable medium of claim 26, wherein thecell-specific signal includes one or more of a secondary synchronizationsignal (SSS) or a physical broadcast channel (PBCH) specific to thecell, and wherein the unified synchronization signal includes one ormore of a primary synchronization signal (PSS), SSS, or PBCHcorresponding to the one or more cells in the zone.